JPS63135037A - Establishing method for data link - Google Patents

Abstract

PURPOSE:To establish next new data link during the establishing of data link between a master station and a slave station by returning the reply from the slave station to the master station with respect to polling information. CONSTITUTION:When the master station transfers a data to a slave station T1, the master station sends polling information to other slave stations (T2, T3) in succession to the data information transmission. Suppose that a transmission request takes place in the slave station T3, the slave station T3 receiving the polling information from the master station returns the reply to the polling information to the master station. The master station receiving the response gives transmission permission to the slave station T3. On the other hand, the slave station T1 receiving the data returns the reception acknowledge of reception enable or reception disable to the master station. Then the master station receives the reception acknowledge. The reception acknowledge is received after the response to the polling information is received because of the difference in the processing speed of the data information and polling information. Thus, while the reception acknowledge to the data transfer is awaited, the acknowledge of polling information is received to select the slave station establishing the data link next.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a system that has a plurality of terminal stations and performs communication processing, and more specifically, the present invention relates to a system that has a plurality of terminal stations and performs communication processing. This invention relates to a method for establishing a data link in a system in which a master station centrally manages a slave station.

(Conventional technology) Polling and
A selection method is known. This polling
As shown in Figure 3, the selecting method has a master station and multiple slave stations connected to the transmission line 6 in the system, and the master station always initiates an operation to establish a data link with the slave stations (centralized management) method. The master station regularly selects one of the multiple slave stations and requests data transmission (polling).
A slave station ready for data transfer responds to the polling and establishes a data link. In addition, timer value information is included in the polling transferred from the master station, and polling is sent to multiple slave stations without waiting for responses from the slave stations, and the above polling is performed after the time allocated to each slave station based on the timer value has elapsed. There is a method in which a response to the information is returned to the master station, and the master station establishes a data link with a slave station having a high priority in the response (for example, see Japanese Patent Laid-Open No. 60-68738).
.

FIG. 4 is a sequence chart when data is transferred from the master station to the slave station of the system shown in FIG. 3 using the conventional selecting method. In the figure and FIG. 4, the master station transmits data frame 1 to one slave station T at the same timing as the polling frame. The slave station T□ receives this data frame 1, and when the processing is completed, the slave station T□ transfers a reception response frame 4 (for example, an ACK frame or a NAK frame) to the master station. The main station receives reception response frame 4 70 hours after sending data frame 1, and completes the selection method. Next, if there is no data transfer to the slave stations, polling frame 2 containing the response time timer value is sent to the slave stations T□, T2. T3, and the polling response frame 3 from the slave station T is sent to the polling frame 2 at the TP determined based on the timer value.
Upon reception after a certain period of time, the master station transmits a transmission permission frame 5 to the slave station T3 and establishes a new data link.

(Problems to be Solved by the Invention) However, in the above data link establishment method, the main station waits for a period from data transfer to reception response (To waiting time).

No action can be taken against the slave station. In addition, the response to polling information (Tp waiting time is usually fast because the slave station is waiting for the polling frame with the transmission level established. In contrast, the response by data transfer (Tp) is fast.
Since the slave side receives the data, processes it, and returns a response after checking the processing result, it takes more time than the response to the polling frame (T p time). Furthermore, the slave station may perform electrical or mechanical operations (
For example, if the process involves screen display, printout, etc.), it takes a considerable amount of time. While waiting for a response, the transmission line is in a ``empty'' state, resulting in a reduction in transmission efficiency and, as a result, a problem in that the processing speed of the system is reduced.

The present invention provides an improved data link establishment method that shortens the time required to establish the next data link after data transfer from the main station as described above, and improves the processing speed of the entire system. The purpose is to

(Means for Solving the Problems) The present invention is directed to a system in which a plurality of slave stations are connected to each other via a transmission line, and a master station centrally manages the plurality of slave stations.

The present invention provides the above system in which, when the master station transfers data information to the slave station, the master station also transfers polling information following the data information, and the slave station requesting a data link with the master station sends a response to the polling information to the master station. By returning this, the master station performs the operation of establishing the next new data link while the data link with the slave station is being established.

(Function) For example, when a master station transfers data to a slave station T, the master station continues to transmit data information to another slave station (T z
, T z). now,
Assuming that a transmission request has been issued to the slave station T3, the slave station T3, which has received the polling information from the master station, returns a response to the polling information to the master station. The master station that receives this response gives transmission permission to the slave station T. On the other hand, the slave station T□ which has received the data returns to the master station a reception response indicating that the data can be received or cannot be received. The main station then receives this reception response. This reception response is normally received after the response to the polling information is received due to the difference in processing speed between data information and polling information.

In this way, while waiting for a received response to a data transfer,
By receiving a response to polling information, it is possible to select the next slave station to establish a data link with, thereby solving the conventional problems.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

First, the system configuration according to this embodiment is the same as that shown in FIG. Here, the subordinate T engineer.

T2. T, each has a unique station address SA.

SA2. SA, and has a station address GA common to all slave stations.

FIG. 2 shows an example of a frame according to this embodiment among the transmission frames used in the system.

FIG. 2(a) is a polling frame that specifies polling information, 7 is a synchronization pattern area (F), and 8 is the above-mentioned common address OA area (GA).

9 is a polling information area (Data), and 10 is a check code area (Fe2).

FIG. 2(b) is a data frame specifying data information, and reference numeral 11 indicates the slave station's unique address SA area (SA
), 12 is a data information area (Data).

FIG. 2(c) shows a polling frame (a) and a data frame (b) as one frame.

Establishment of a data link in this embodiment in such a system configuration is performed as shown in FIG.

If there is information to be transmitted by the master station to the slave station T□, the master station sets the unique address area SA of the data frame shown in FIG. 2(b) as SA and starts transmission. When the transmission of data frame 1 is completed, the main station subsequently starts transmitting polling frame 2. This special number subordinate station T□
, T2. At T, slave station T□ processes data frame 1 and polling frame 2 addressed to its own station, and slave stations T, , T, process polling frame 2.

Here, assuming that a transmission request has occurred at the slave station T3, the slave station T3 transmits a polling response frame 3 to the master station based on the data information in the polling frame 2. Further, when there are transmission requests from a plurality of slave stations, each slave station transmits a polling response frame 3 after a response time determined for each slave station based on the data information in the polling frame 2 has elapsed. Then, the master station selects the slave station with the highest priority among the responses from the plurality of slave stations. The operation from sending the polling frame to receiving the polling response frame is the same as the conventional method, and does not depend on the polling method or the number of slave stations.

The master station receives and processes the polling response frame 3 from the slave station T, T1 hours after sending the polling frame, and subsequently processes the reception response frame 4 from the slave station T1 after sending the data frame. Receive after hours. As mentioned in the prior art section, due to the difference in processing speed of the slave station for polling frames and data frames, generally T
, the maximum time < Tl) holds true. After receiving the reception response frame 4, the transmission permission frame 5 corresponding to the already received polling response frame 3 is transmitted to the slave station T, and a new data link is established. Furthermore, even if T,=To, maximum time of T>minimum time of TO, and reception of polling response frame 3 at the main station is delayed than reception of reception response frame 4,
Since each process is performed depending on the content of the frame, no inconvenience occurs.

1. As another embodiment of the present invention, even if the data frame 1 and polling frame 2 that the master station continuously transmits are transmitted as one frame as shown in FIG. 2(C), the slave station T , T2. It is also possible to operate the T and side in the same manner as in the previous embodiment.

(Effects of the Invention) As described above in detail, according to the present invention, the main station transmits a polling frame following a data frame,
Since the next slave station to establish a data link can be selected by the time the reception response frame is received, the time required to establish a data link is shortened, and an improvement in the processing speed of the entire system can be expected.

The present invention can be implemented without depending on the number of slave stations installed or the polling method, so it can be widely applied to various systems.

[Brief explanation of the drawing]

FIG. 1 is a sequence chart for explaining the procedure for establishing a data link according to an embodiment of the present invention, FIG. 2 is a diagram showing a frame format used in this embodiment, and FIG.
The figure is a block diagram of a system that requires establishment of a data link, and FIG. 4 is a sequence chart for explaining a conventional procedure for establishing a data link. 1...Data frame, 2...Polling frame. 3... Polling response frame, 4... Reception response frame, 5... Transmission permission frame,
6...Transmission line, 7...Synchronization pattern area. 8...Common address GA area. 9...Polling information area. 10...Check code area, 11...Unique address area, 12...Data information area.

Claims (1)

[Claims] In a system in which a plurality of slave stations are connected to each other via a transmission line and a master station centrally manages the plurality of slave stations, when the master station transfers data information to the slave station, the master station transmits polling information following the data information. In this process, the slave station that requests a data link with the master station returns a response to the polling information to the master station, so that the master station can wait for the establishment of the next new data link while the data link with the slave station is being established. A method for establishing a data link characterized by performing the following actions.